[RFC 1/2] kernel patch for dump user space stack tool

From: Tu, Xiaobing
Date: Wed Apr 11 2012 - 04:07:48 EST


From: xiaobing tu <xiaobing.tu@xxxxxxxxx>

Here is the kernel patch for this tool, The idea is to output user space stack call-chain from /proc/xxx/stack, currently, /proc/xxx/stack only output kernel stack call chain. We extend it to output user space call chain in hex format

Signed-off-by: yanmin zhang <yanmin_zhang@xxxxxxxxxxxxxxx>
Signed-off-by: xiaobing tu <xiaobing.tu@xxxxxxxxx>
---
arch/x86/kernel/stacktrace.c | 55 ++++++++++++++++++++++++++++++++++++++++++
fs/proc/base.c | 19 +++++++++++++-
include/linux/stacktrace.h | 5 +++-
3 files changed, 77 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c index fdd0c64..d802f05 100644
--- a/arch/x86/kernel/stacktrace.c
+++ b/arch/x86/kernel/stacktrace.c
@@ -7,6 +7,7 @@
#include <linux/stacktrace.h>
#include <linux/module.h>
#include <linux/uaccess.h>
+#include <linux/mm.h>
#include <asm/stacktrace.h>

static int save_stack_stack(void *data, char *name) @@ -144,3 +145,57 @@ void save_stack_trace_user(struct stack_trace *trace)
trace->entries[trace->nr_entries++] = ULONG_MAX; }

+static inline void __save_stack_trace_user_task(struct task_struct *task,
+ struct stack_trace *trace)
+{
+ const struct pt_regs *regs = task_pt_regs(task);
+ const void __user *fp;
+ unsigned long addr;
+
+ if (task != current && task->state == TASK_RUNNING && task->on_cpu) {
+ /* To trap into kernel at least once */
+ smp_send_reschedule(task_cpu(task));
+ }
+
+ fp = (const void __user *)regs->bp;
+ if (trace->nr_entries < trace->max_entries)
+ trace->entries[trace->nr_entries++] = regs->ip;
+
+ while (trace->nr_entries < trace->max_entries) {
+ struct stack_frame_user frame;
+
+ frame.next_fp = NULL;
+ frame.ret_addr = 0;
+
+ addr = (unsigned long)fp;
+ if (!access_process_vm(task, addr, (void *)&frame,
+ sizeof(frame), 0))
+ break;
+ if ((unsigned long)fp < regs->sp)
+ break;
+ if (frame.ret_addr) {
+ trace->entries[trace->nr_entries++] =
+ frame.ret_addr;
+ }
+ if (fp == frame.next_fp)
+ break;
+ fp = frame.next_fp;
+ }
+}
+
+void save_stack_trace_user_task(struct task_struct *task,
+ struct stack_trace *trace)
+{
+ if (task == current || !task) {
+ save_stack_trace_user(trace);
+ return;
+ }
+
+ if (task->mm)
+ __save_stack_trace_user_task(task, trace);
+
+ if (trace->nr_entries < trace->max_entries)
+ trace->entries[trace->nr_entries++] = ULONG_MAX; }
+EXPORT_SYMBOL_GPL(save_stack_trace_user_task);
+
diff --git a/fs/proc/base.c b/fs/proc/base.c index d4548dd..603e708 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -327,8 +327,25 @@ static int proc_pid_stack(struct seq_file *m, struct pid_namespace *ns,
seq_printf(m, "[<%pK>] %pS\n",
(void *)entries[i], (void *)entries[i]);
}
- unlock_trace(task);
+ } else
+ goto out;
+
+ trace.nr_entries = 0;
+ trace.max_entries = MAX_STACK_TRACE_DEPTH;
+ trace.entries = entries;
+ trace.skip = 0;
+
+ seq_printf(m, "userspace\n");
+
+ save_stack_trace_user_task(task, &trace);
+
+ for (i = 0; i < trace.nr_entries; i++) {
+ if (entries[i] != ULONG_MAX)
+ seq_printf(m, "%p\n", (void *)entries[i]);
}
+ unlock_trace(task);
+
+out:
kfree(entries);

return err;
diff --git a/include/linux/stacktrace.h b/include/linux/stacktrace.h index 115b570..65e9ae4 100644
--- a/include/linux/stacktrace.h
+++ b/include/linux/stacktrace.h
@@ -23,8 +23,11 @@ extern void print_stack_trace(struct stack_trace *trace, int spaces);

#ifdef CONFIG_USER_STACKTRACE_SUPPORT
extern void save_stack_trace_user(struct stack_trace *trace);
+extern void save_stack_trace_user_task(struct task_struct *task,
+ struct stack_trace *trace);
#else
-# define save_stack_trace_user(trace) do { } while (0)
+# define save_stack_trace_user(trace) do { } while (0)
+# define save_stack_trace_user_task(task, trace) do { } while (0)
#endif

#else
--
1.7.6
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/